Protective effects of dietary docosahexaenoic acid against kainate-inducedretinal degeneration in rats

PURPOSE. To investigate the role played by docosahexaenoic acid (DHA) in th e retina, and more specifically its ability to protect the retina from kain ic acid (KA)-induced retinal damage. METHODS. Three-week-old female Wistar rats were used. DHA. (1000 mg/kg per day) was fed to the rats for 7, 14, and 28 days, and the concentrations of DHA and arachidonic acid (AB) in the retina and serum mere measured. In ano ther group of rats, the right eyes were injected intravitreally with 3.12 n anomoles KA after DHA supplementation for 14 days. Electroretinograms (ERGs ) elicited by different stimulus intensities were recorded before and on da ys 1, 7, and 14 after the KA injection. The amplitudes and implicit times o f the a- and b-waves were compared. The number of cells in the ganglion cel l layer (GCL) and inner nuclear layer (INL) mere compared by histopathologi c examination. RESULTS. The concentration of DHA in the serum and retina increased after D HA supplementation. The concentration of AA in serum decreased with DHA sup plementation, but the concentration of AA in retina did not show any signif icant change. The b-waves of the ERGs recorded after KA injection were sign ificantly attenuated in both groups of rats. However, the attenuation was s ignificantly less in the DHA-supplemented rats than in gum arabic-supplemen ted control rats. The numbers of cells in the INL and GCL were significantl y higher in DHA-supplemented rats. CONCLUSIONS. These results indicate that DHA supplementation can partially counteract KA neurotoxicity in the rat retina. DHA may play a role in modul ating neuronal excitability by reducing KA-induced responses in the retina.